JP4640729B2 - Preform molding method, preform and casing - Google Patents

Description

The present invention relates to a method for forming a preform made of a synthetic resin having a colored layer whose layer thickness is changed to a gradation, a preform obtained by the molding method, and a synthetic resin candy decorated by changing the color density to a gradation About the body.

Housings made of polyethylene terephthalate (PET) resin and the like are used in various fields such as beverages, foods, and cosmetics, and various decorating methods are adopted to differentiate them as products. In many cases, the case is decorated with a printed shrink film. However, Patent Document 1 describes a case in which a laminated structure is formed and a preform in which a colored layer is intermittently formed on an intermediate layer is blow-molded.
Japanese Patent Laid-Open No. 2-98409

  The inventors of the present application decorate the casing by changing the shade of color in the vertical direction in a biaxial stretch blow-molded bottle having transparency, such as made of PET resin, to reveal a gradation related to the color density. Worked on the development of technology. Among them, the method described in Patent Document 1 was used to form an intermediate layer with a colored resin in a preform and biaxially stretch blow-molded, but although a slight gradation of gradation can appear, the degree of gradation However, it was limited and was unsatisfactory from the point of decorating property.

  Therefore, the present invention has an object to gradually change the thickness of the colored layer made of the colored resin in the preform in the up-down direction, so that the gradation related to the coloring density is highly developed, and thus far An object of the present invention is to provide a biaxially stretched blow molded synthetic resin casing having a decorative property not found in the present invention.

Of the present invention for solving the above technical problems, claims 1 to 6 relate to a preform molding method, and of these, the molding method of the invention according to claim 1
A method of forming a preform for biaxial stretch blow molding,
A colored resin is primarily injected into a short shot state into a mold cavity through a gate located opposite the center of the bottom,
Secondary injection of the main material resin as the main material for sequentially forming the preform after the elapse of a predetermined waiting time from the end of the primary injection,
By adjusting the waiting time, the main material resin is caused to flow through the central portion of the colored resin located in the mold cavity in a short shot state by secondary injection,
A colored layer made of colored resin is formed in the vicinity of the inner peripheral surface and the outer peripheral surface of the preform in the form of a double cylinder, and a gradation region is formed in which the thickness of the colored layer gradually decreases in the upward direction of the preform. What I did,
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According to the molding method of the first aspect, the colored resin is injected in a short shot by the primary injection. After the primary injection is completed, the main resin is sequentially injected after a predetermined waiting time. To do. In this manner, the portion in contact with the cavity mold surface and the core mold surface as the standby time elapses and the vicinity thereof (hereinafter, may be collectively referred to as the mold surface vicinity portion) are short-shot. Cooling of the injected colored resin proceeds, and in this portion, cooling and solidification of the resin or an increase in melt viscosity proceeds.
Here, by appropriately adjusting and deciding the waiting time, the colored resin that has been primarily injected is cooled as described above in the vicinity of the mold surface, and kept at a high temperature in the vicinity of the central portion of the cavity. State.

Then, in the above-described state, when the main material resin is sequentially secondarily injected, the main material resin in the molten state passes through the gate located at the center of the bottom of the preform, and the central portion of the cavity of the colored resin. A portion of the colored resin is dragged together so as to penetrate through the high temperature portion of the liquid, and the fluid flows in the cavity toward the portion corresponding to the upper end portion of the mouth tube portion, and is filled in the cavity.
At this time, the colored resin located in the vicinity of the mold surface, particularly in the very vicinity, hardly flows but remains in the primary injection position, and the colored resin is stretched in the flow direction. As a result, this colored resin In particular, the layer thickness of the flow front part gradually decreases in a gradation toward the flow direction.

In the preform molded by sequential injection as described above, a colored layer made of a colored resin is formed in a double cylindrical shape near the inner peripheral surface and the outer peripheral surface, and the layer thickness of the colored layer is the preform. A gradation region that gradually decreases toward the upper end is formed.
Depending on the molding conditions or the height position of the preform, a thin main resin layer is formed on the inner side or the outer side of the colored layer, and the inner resin surface (innermost layer) or outer periphery is formed by this main resin layer. Since the surface (outermost layer) is formed, the portion including the inner peripheral surface or the outer peripheral surface is described here in terms of the inner peripheral surface and the vicinity of the outer peripheral surface.

  As described above, the basic technical idea of the molding method according to claim 1 is that a short shot is made in the cavity by interposing an appropriate waiting time between the primary injection and the second injection in the sequential injection molding. Utilizing the degree of cooling of the colored resin near the mold surface and the center, a part of the colored resin is stretched in the flow direction by the flow of the main resin injected later to form a gradation region related to the layer thickness. It is in.

  The gradation level related to the layer thickness, that is, the mode of change of the layer thickness is determined by the sequential injection of the injection amount of the primary injection and the secondary injection, the injection speed, the injection pressure, the injection temperature, the standby time, etc. according to the purpose. And the melt viscosity of the resin used can be controlled.

  According to a second aspect of the present invention, there is provided the molding method according to the first aspect, wherein the gradation level related to the thickness of the colored layer is controlled by a combination of the standby time, the injection speed of the secondary injection, and the injection pressure. In what you did.

According to the above method of the second aspect, it is possible to relatively easily control the degree of gradation related to the layer thickness of the colored layer by the standby time, the injection speed of the secondary injection, and the injection pressure among the sequential injection conditions. .
By shortening the waiting time, increasing the injection speed of the secondary injection, and increasing the injection pressure, the layer thickness can be changed more gently, and a string-like layer is formed at the tip of the colored layer. You can also.

  According to a third aspect of the present invention, there is provided a molding method according to the first or second aspect, wherein a synthetic resin obtained by coloring a main material resin is used as the colored resin.

  In the molding method according to the third aspect, the entire preform is formed from the same resin, and stable molding is possible by molding the entire preform from the same resin.

  The molding method of the invention described in claim 4 is that, in the invention of claim 1 or 2, the melt viscosity of the colored resin is set lower than that of the main resin.

  In the molding method according to claim 4, the colored resin in the short shot state is deformed by the action of the flow of the main material resin penetrating through the central portion, but this action is more effective by making the colored resin have a low viscosity. It becomes possible to change the layer thickness of the tip portion more like a string.

  According to a fifth aspect of the present invention, there is provided the molding method according to the first, second, third or fourth aspect, wherein the main resin and the colored resin are both made of a resin having transparency.

  By the molding method according to claim 5, it is possible to more effectively reveal the gradation effect related to the color density by transmitting light in the final product casing, and to provide a casing having an unprecedented decoration effect. Can be provided.

  According to a sixth aspect of the present invention, there is provided the molding method according to the first, second, third, fourth or fifth aspect, wherein a predetermined amount of the main material resin is pre-injected before the primary injection. .

In the sequential injection molding method of the preform of the present invention, primary injection by a series of colored resins, standby time, and secondary injection by a main material resin are fundamental. A predetermined amount of main material resin is injected before.
In this way, by injecting a predetermined amount of the main material resin before the primary injection, it is possible to appropriately set the formation position of the colored layer in the preform according to the purpose of decoration in the casing.

  In addition, during primary injection with colored resin after preliminary injection, the colored resin is extended while extending the main resin to the mold surface so as to penetrate the central portion of the main resin that has been pre-injected in a short shot. The outer peripheral surface (outermost layer) and inner peripheral surface (innermost layer) of the preform can also be composed of the main resin, and in the case of the casing product, the contents do not come into direct contact with the colored resin. Can be used with heart.

Next, the invention according to claim 7 relates to a preform, and the means of the invention firstly injects colored resin into a mold cavity in a short shot state through a gate opposed to the center of the bottom. A preform formed by a sequential injection molding method in which a main material resin, which is a main material for forming a preform next, is secondarily injected after a predetermined waiting time has elapsed,
In the vicinity of the inner peripheral surface and the outer peripheral surface, there is a colored layer made of a colored resin in a double cylindrical shape, and a gradation region is formed in which the thickness of the colored layer gradually decreases toward the upper end of the preform. ,
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  The preform having the above-described structure according to claim 7 can be obtained by the molding method according to any one of claims 1 to 6 described above, and the preform is biaxially stretched and blow-molded to obtain a coloring concentration by a colored layer made of a colored resin. It is possible to provide a casing having an unprecedented decorative property in which such gradation is highly expressed.

  Next, the invention according to claim 8 and claim 9 relates to a casing, and the means of the invention according to claim 8 is that a biaxially-stretched blow molded synthetic resin casing has a certain height. Over the range, a colored layer is formed in the vicinity of the inner peripheral surface and the outer peripheral surface in the form of a double cylinder made of a colored resin and the layer thickness gradually decreases upward. The gradation related to is appearing and decorated.

  The casing according to claim 8 can be obtained by biaxial stretch blow molding of the preform obtained by the molding method according to claims 1 to 6 described above. It is possible to provide a highly-developed case having unprecedented decorating properties.

  The invention according to claim 9 is the invention according to claim 8, wherein, in the PET resin housing, from a colored transparent state upward in a certain height range from the vicinity of the bottom to the shoulder. A gradation related to a coloring density that gradually and gradually changes to a colorless and transparent state has appeared.

  With the above-described configuration according to claim 9, an unprecedented decorative property, in which a gradation that gradually changes continuously from a colored state to a colorless state appears in a certain height range from the vicinity of the bottom to the shoulder. A casing made of PET resin can be provided.

The present invention is the above-described method and configuration, and has the following effects.
First, claims 1 to 6 relate to a preform molding method.
In the invention according to claim 1, a colored layer made of a colored resin is formed in a double cylindrical shape in the vicinity of the inner peripheral surface and the outer peripheral surface by sequential injection molding with a waiting time in between, and the colored layer Thus, it is possible to obtain a preform in which a gradation region in which the layer thickness gradually decreases toward the upper end of the preform.

  In the invention according to claim 2, the layer thickness can be changed more gently by shortening the waiting time, increasing the injection speed of the secondary injection, and increasing the injection pressure. A string-like layer can also be formed at the tip of each.

  In the invention of claim 3, the entire preform is formed of the same resin, and stable molding is possible by molding the entire preform with the same resin.

  In the invention described in claim 4, by making the colored resin have a low viscosity, the tip of the colored layer can be easily changed into a string shape.

  According to the fifth aspect of the present invention, the gradation effect can be more effectively revealed by the transmission of light, and a housing having an unprecedented decorative effect can be provided.

  In the invention of claim 6, by pre-injecting a predetermined amount of the main material resin before the primary injection, the formation position of the colored layer in the preform can be determined according to the decoration purpose in the casing. It can be set as appropriate, and the outer peripheral surface and inner peripheral surface of the preform can be composed of the main material resin. In the case of the casing product, the contents do not directly contact the colored resin, so that it can be used with confidence.

  The invention according to claim 7 relates to a preform, and the preform is biaxially stretch blow-molded, and a gradation related to the color density is highly developed by a colored layer made of a colored resin. A casing having a decorative property can be provided.

Next, invention of Claim 8 and Claim 9 concerns a housing.
In the invention according to claim 8, it is possible to provide a casing having an unprecedented decorative property in which a gradation relating to the coloring density is highly expressed by the colored layer.

  In the invention of claim 9, a gradation region related to a coloring density that gradually and gradually changes from a colored state to a colorless state appears in a certain height range from the vicinity of the bottom to the shoulder. A PET resin casing having unprecedented decorativeness can be provided.

Hereinafter, embodiments of the preform molding method, the preform, and the casing of the present invention will be described with reference to examples and drawings.
FIG. 1 is a schematic explanatory view showing an example of a sequential injection pattern applied to the preform molding method of the present invention, and FIGS. 2 and 3 are cross-sectional views showing an example of a mold used in the preform molding method of the present invention. It is.

  2 and 3 includes a core mold 2 and a cavity mold 3, and a cavity 4 corresponding to a test tubular preform is formed. And the gate 5 is formed in the position corresponding to the center part of the bottom part 107 (refer FIG. 5) of the preform 101, The molten resin inject | emitted by the injection pattern shown by FIG. 1 is supplied from this gate 5, The cavity 4 flows toward the portion corresponding to the mouth tube portion 104 to fill the cavity 4.

  The injection pattern schematically shown in FIG. 1 is an example of a sequential injection pattern. First, the primary injection J1 with the colored resin 12 is performed between times t1 and t2, and after the standby time Ht between t2 and t3 has elapsed, Next, the secondary injection J2 by the main material resin 11 is sequentially performed between t3 and t5.

  4 (a), 4 (b), and 4 (c) are schematic explanatory views showing states of the injection pattern at time t2, time t4, and time t5, respectively, and the cavity 4 is colored in a short shot at time t2. The resin 12 is filled in a range of about ¼ from the bottom (see FIGS. 2, 3, and 4 (a)).

  Next, the supply of the colored resin is stopped at time t2 in the above filling state, and the mold surface of the cavity mold 3 and the mold of the core mold 2 are multi-faced as the standby time Ht (t2 to t3) progresses. Cooling of the colored resin 12 injected in a short shot progresses in the vicinity of the surfaces 12a and 12b (see the enlarged view in FIG. 3), and cooling and solidification of the resin or an increase in melt viscosity proceeds in the portion. .

  Then, in this state, when the secondary injection J2 by the main material resin 11 is successively performed, as shown schematically in FIG. Through the gate 5 located opposite to the center of the bottom 107, the colored resin 12 penetrates through the high temperature portion of the central portion 12c of the cavity 4 (see the enlarged view in FIG. 3) and further breaks through the tip portion 13 to The fluid flows in the cavity 4 toward the portion corresponding to the upper end portion of the mouth tube portion 104 while flowing and deforming so that the portions are dragged together (see the white arrow in FIG. 4B). Further, the main material resin 11 flows in, and the state shown in FIG.

At this time, the colored resin 12 positioned very close to the mold surface hardly flows and remains at the position where the primary injection J1 is performed, so that the colored resin 12 positioned at the central portion 12c is stretched in the flow direction. Flow deformation.
4B shows an example in which the main material resin 11 flows through the distal end portion 13 of the colored resin 12, but it is not always necessary to break through the distal end portion 13 in this way. Depending on the purpose of decoration, the main material resin 11 can be flowed without breaking the tip portion 13.

FIG. 5 shows a PET resin as the main material resin 11 and the same PET resin colored with a pigment as the colored resin 12, and a preform 101 molded by the sequential injection molding method as described above is partially cut vertically. FIG.
In this preform 101, the colored layer 103 is formed in a double cylindrical shape near the inner peripheral surface and the outer peripheral surface, and the layer thickness is substantially constant in a height range h1 corresponding to the substantially lower half of the preform 101. In the upper height range h2, the shape changes to a string shape, and a gradation region 110 appears with a layer thickness that gradually decreases and changes toward the upper side of the preform 101.

  Next, FIG. 6 shows a casing 201 having a cylindrical body portion 206 obtained by biaxial blow-extrusion molding of the preform 101 of FIG. 5, and has a height from the bottom portion 207 to a substantially central height position. The range h1 is a colored portion having substantially the same density. Further, in the height range h1 up to just below the neck ring 205 above that, a gradation region 210 relating to the coloring density is formed in which the degree of coloring gradually changes to a colorless and transparent state. The upper portion including the mouth tube portion 204 is a colorless and transparent region.

  As mentioned above, although embodiment of this invention was described according to the Example, this invention is not limited to these Examples. The synthetic resin to be used is not limited to PET resin, but it is possible to use resins conventionally used for biaxially stretched blow molded casings such as PP resin, and change the melt viscosity of the colored resin according to the purpose. It is also possible to use other types of resins without being limited to the same type. The main material resin is not limited to colorless and transparent, and may be colored, transparent, translucent, or opaque depending on the purpose.

  In addition to the injection pattern of the sequential injection molding described in FIG. 1, other injection patterns can be used depending on the purpose. FIG. 7 shows another pattern of sequential injection molding applied to the present invention, in which a predetermined amount of main material resin 11 is pre-injected JP before primary injection J1. Thus, by injecting a predetermined amount of the main material resin before the primary injection J1, the lower end position of the colored layer 103 in the preform 101 is not limited to the bottom 107 as in the embodiment shown in FIG. Depending on the injection amount of the preliminary injection JP, it can be raised to a predetermined position, and the formation position of the colored layer 103 can be changed according to the decoration purpose in the casing 201.

  Further, during the primary injection J1 with the colored resin after the preliminary injection JP, the main resin is stretched on the mold surface so as to penetrate the central portion of the main resin pre-injected in a short shot shape. The colored resin can be flowed while the outer peripheral surface (outermost layer) and inner peripheral surface (innermost layer) of the preform can be composed of the main resin depending on the injection conditions. It can be used with confidence because it does not contact the resin.

  According to the preform molding method of the present invention, it is possible to provide a housing having an unprecedented decorative property, in which a gradation of color density is highly manifested by the colored layer, thereby differentiating the product. It is expected to be used widely.

It is a schematic explanatory drawing which shows an example of the sequential injection pattern applied to the preform shaping | molding method of this invention. It is a vertical front view which shows an example of the metal mold | die for preform shaping | molding. FIG. 3 is a plan sectional view taken along line AA of the mold of FIG. 2. It is a schematic explanatory drawing which shows the filling process of the molten resin to the metal mold cavity by the injection pattern of FIG. FIG. 2 is a front view showing a part of the preform formed by the injection pattern of FIG. FIG. 6 is a front view of a casing obtained by biaxial stretching blow molding the preform of FIG. 5. It is a schematic explanatory drawing which shows the other example of a sequential injection pattern.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1; Metal mold | die 2; Core metal mold | die 3; Cavity metal mold | die 4; Cavity 5; Gate 11; Main resin 12; Colored resin 12a, 12b; Part 101; Preform 102; Main material resin layer 103; Colored layer 104; Mouth part 105; Neck ring 106; Body part 107; Bottom part 110; Gradation area 201; Part 206; trunk 207; bottom 210; gradation area h1; height range h2; height range

Claims (9)

The colored resin (12) is primarily injected in a short shot state (J1) into the cavity (4) of the mold (1) through the gate (5) located at the center of the bottom (107), and the primary injection is performed. After the elapse of the standby time (Ht) from the end of (J1), the main material resin (11) as the main material for forming the preform (101) is sequentially subjected to secondary injection (J2), and the standby time ( By adjusting the Ht), the main part resin (11) is removed by the secondary injection (J2) and the central part (12c) of the colored resin (12) located in the mold (1) cavity (4) in the short shot state. To form a colored layer (103) made of a colored resin (12) in the form of a double cylinder in the vicinity of the inner peripheral surface and the outer peripheral surface of the preform (101), and the colored layer (103 A preform molding method for biaxial stretch blow molding in which a gradation region (101) in which the layer thickness of () gradually decreases in the upward direction of the preform (101) is formed. The preform molding according to claim 1, wherein the degree of gradation related to the layer thickness of the colored layer (103) is controlled by a combination of the standby time (Ht), the injection speed of the secondary injection (J2), and the injection pressure. Method. The preform molding method according to claim 1 or 2, wherein a synthetic resin colored with a main resin (11) is used as the colored resin (12). The preform molding method according to claim 1 or 2, wherein the colored resin (12) has a lower melt viscosity than the main material resin (11). The preform molding method according to claim 1, 2, 3, or 4, wherein the main resin (11) and the colored resin (12) are both transparent resins. The preform molding method according to claim 1, 2, 3, 4, or 5, wherein a predetermined amount of the main material resin (11) is pre-injected (JP) before the primary injection (J1). The colored resin (12) is primarily injected into a short shot state (J1) into the cavity (4) of the mold (1) through the gate (5) located opposite the center of the bottom (107), and a predetermined waiting time is reached. After the lapse of (Ht), the preform (101) was molded by a sequential injection molding method in which the main resin (11), which is the main material for forming the preform (101), is secondarily injected (J2). A colored layer (103) made of a colored resin (12) in the form of a double cylinder in the vicinity of the inner peripheral surface and the outer peripheral surface, and the thickness of the colored layer (103) is in the upper end direction of the preform (101) A biaxial stretch blow molding preform characterized in that a gradation region (101) gradually decreasing toward the surface is formed. A colored layer (103) consisting of a colored resin (12) is formed in the vicinity of the inner and outer peripheral surfaces over a certain height range, consisting of a colored resin (12), and the layer thickness gradually decreases upward. A biaxially-stretched blow molded synthetic resin casing in which a gradation relating to the color density appears and is decorated by the colored layer (103). It is made of polyethylene terephthalate resin and has a certain height range from the vicinity of the bottom part (207) to the shoulder part (205a), and it relates to the coloring concentration that gradually and gradually changes from the colored transparent state to the colorless transparent state upward. The synthetic resin casing according to claim 8, wherein gradation is revealed.